Application of an extended GTD model to synthetic aperture radar simulation

Abstract

An urban scene has very complex variety of length scales ranging from much larger to much smaller than the wavelength of the radiation emitted by a Synthetic Aperture Radar (SAR). The exact solution to this scattering problem requires the solution of Maxwell's equations for the combination of source and scattering objects present in the scene, which for any reasonable size target area is computationally too intensive to be realistic. Hence while a 'numerically exact' solution at present is not possible, some form of approprite modeffing scheme is used as is usual in electromagnetic problems.The geometrical theory of diffraction (GTD) gives an accurate result with a practical amount of computation. This theory is based on the fact that the most important contributions towards the scattered field come from an area in the neighbourhood of some critical points on the scattering surface. For a planar surface, three critical points may be regarded: specular, edge-diffraction and corner-diffraction points. A physical optics version of GTD was taken with the approximate diffraction coefficients derived using physical optics approximations to canonical problems.In this paper, the new model is described in addition to an overview of a ray-tracing procedure adopted and its resultant images.

Images of urban areas by a synthetic aperture radar simulator

“…The returned signal bahaves very much as expected but its accuracy will only become clear by comparison with other models. One such model is an extended GTD model which would have the added advantage of including diffraction in its assumptions and will be discussed in another paper [2] to be presented as an oral session during this conference.…”